TURPENTINE. 5 
slightly greater extent in turpentine from virgin gum. -Hxamination 
with a polariscope shows that American turpentine from the South- 
ern yellow pine generally rotates a plane of polarized light to the 
right. Therefore, the pimene in American turpentine is called dextro- 
alpha pinene. On the other hand, French turpentine rotates the 
plane of polarized light to the left, because of the presence of the 
variety of pinene known as laevo-alpha pinene. 
Among the other terpenes which have been identified in turpen- 
tine oil may be mentioned beta-pinene or nopinene, camphene, syl- 
vestrene, and dipentene. ‘These occur only in small quantities. The 
two mentioned last are also found in destructively distilled wood 
turpentine. 
The pinene in turpentine obtained from the Cuban or slash pine 
(Pinus caribea or heterophylla) is laevorotatory, like the French tur- 
pentine. The preponderance of the longleaf yellow pine (Pinus pa- 
lustris) in the southern pineries accounts for the fact° that American 
turpentine is generally dextrorotatory. 
Since turpentine consists chiefly of pinene, its physical and chemical 
properties might be expected to be similar to those of pinene. The 
differences between them are due to the presence of small and vary- 
ing quantities of other terpenes and of certain oxidation prod- 
ucts. Pure alpha pinene boils at 155° to 156° C., has a specific 
gravity of from 0.858 to 0.860 at 20° C., and a refractive index of 
1.4655 at 21° C. Pure beta pinene boils at 162° to 163° C., has a 
specific gravity of about 0.867 at 20° C. and a refractive index of 
1.476 at 20°C. Accordingly, turpentine begins to distill around 155° 
C., has a specific gravity, at 20° C., of from 0.858 to 0.872, and a re- 
fractive index of from 1.468 to 1.478 at 20° C. 
Chemically speaking, turpentine is a highly unsaturated body. It 
combines directly with oxygen, chlorin, bromin, iodin, hydrogen 
chlorid, nitric acid, sulphuric acid, and many other chemically active 
substances. On standing for some time in a partially filled container, 
especially when exposed to the light, or on exposure to the air for a 
shorter period in the form of a thin film, turpentine absorbs oxygen 
from the air (becomes oxidized). At the same time small quanti- 
ties of hydrogen peroxid are-liberated. It will be noticed that the 
cork stopper from a bottle partially filled with turpentine is bleached, 
like the cork in a bottle of hydrogen peroxid. As a result of the 
absorption of oxygen, the turpentine becomes more viscous and oily 
and turns yellow, a solid white deposit often forming at the bottom of 
the bottle. The odor becomes sharp and disagreeable, the specific 
gravity, the refractive index, and the boiling point are raised, and 
the percentage distillmg up to certain limits’ becomes less. Small 
quantities of acetic and other acids are formed in the turpentine. 
1 Ninety per cent up to 170° C. is the specified requirement. 
